In recent years, a CBS (Cell Broadcast Service) has been used as an emergency information distribution system in a mobile network. The CBS notifies cellular phone terminals present in a target area to which emergency information is distributed of the emergency information by a simultaneous broadcast. In addition, an ETWS (Earthquake and Tsunami Warning System) is prescribed in order to deal with an increase in speed of disaster notification, and flexibility of a distribution area.
For example, the increase in speed of the disaster notification is achieved by separately distributing two types of signals of a first report to distribute the most urgent minimum information portion, such as “occurrence of earthquake”, by the fastest speed, and a second report to distribute supplementary information, such as seismic intensity and an epicenter of the earthquake.
Furthermore, the flexibility of the distribution area is achieved by properly using the distribution area at three levels, a Cell level, a TA (Tracking Area) level, and an EA (Emergency Area) level.
Here, in relation to the flexibility of the distribution area, Patent Literature 1 discloses a configuration in which the distribution area is designated in a wide region unit or sector unit as the distribution area of an emergency message.